1. Field of the Invention
The present invention relates to signal recognition, and more particularly to a method and an apparatus for determining the possibility of pattern recognition of time series signal.
2. Description of Related Art
A time series signal is a signal of which the value is varied according to the elapse of the time. As examples of the time series signal, there are a speech signal, a handwritten character signal, and a gesture signal.
Recognition of the contents included in the time series signal is referred to as the pattern recognition of the time series signal. As a representative example of a pattern recognition of a time series signal, there is the speech recognition.
The speech recognition allows a machine to understand the usual speech of human to perform the operations according to the understood speech. The technique of the speech recognition allows information to be obtained at a long distance while the human does not directly move by the development of the computer and information communication, and thus the equipments composed of a system which is operated according to the speech has been continuously developed.
Various speech recognition application systems have been developed on the basis of the speech recognition technique, and, among them, there is a system for notifying desired information according to the language spoken by a user. For example, assuming that there is a telephone number guide system of any group, a system for displaying the telephone number of the corresponding department on the monitor if a user speaks the name of the department to be searched in his/her speech can be considered.
In a pattern recognizing system of the time series signal, including the speech recognizing system, it is most preferable that, while the user does not recognize the existence of the pattern recognizing system, the environment which is likely to exchange the contents included in the pattern with the person is made. However, it is very difficult to embodying such system. In the pattern recognizing system of the time series signal, a method of determining the possibility of the pattern recognition, allowing the machine to perform the pattern recognition with respect to the portion which the pattern can be recognized and allowing it to be connected to a person with respect to the portion which the pattern can not be recognized has been studied in the present technical level.
For example, in the telephone number guide system, in case that the user speaks with the speech which cannot be recognized by the speech recognizing system or the user requires the name of the department which does not exist in the database of the speech recognizing system, it is connected to the human operator to solve the problem.
However, in the conventional art, there is a problem that the capability for determining whether the pattern can be recognized by the pattern recognizing system of the time series signal depends on the pattern recognition ratio itself. In other words, the system having excellent pattern recognition also has the excellent capability for determining whether the pattern cannot be recognized, but the system having inferior pattern recognition also has the inferior capability for determining whether the pattern cannot be recognized.
The same problem is generated even in case that the pattern recognition ratio is varied according to the variation of the environment of the same system. That is, conventional system can be operated well in environment that the pattern can be recognized well so that the system needs not be connected to the human operator, but the system can not determine that the pattern can not be recognized in the environment that the pattern cannot be recognized-well so that the system need be connected to the human operator. Accordingly, the system continuously tries to recognize the pattern instead of connecting it to the human operator, thereby giving the inconvenience to the user.